Biomedical subjects

Helmut Denk

Publications and source records attributed to Helmut Denk.

At least 19 recordsLinked to original sources

PubMed2006

24-norUrsodeoxycholic acid is superior to ursodeoxycholic acid in the treatment of sclerosing cholangitis in Mdr2 (Abcb4) knockout mice.

BACKGROUND & AIMS: Current therapy for primary sclerosing cholangitis is of limited efficacy. Multidrug resistance gene 2 knockout mice (Mdr2(-/-)) represent a well-characterized model for sclerosing cholangitis. Experiments were performed to test in such mice the therapeutic effects of 24-norUrsodeoxycholic acid, a C(23) homologue of ursodeoxycholic acid with 1 fewer methylene group in its side chain. METHODS: Mdr2(-/-) mice were fed a diet containing 24-norUrsodeoxycholic acid (0.5% wt/wt) or ursodeoxycholic acid (0.5% wt/wt) as a clinical comparator for 4 weeks; controls received standard chow. Effects on serum liver tests, liver histology, markers of inflammation and fibrosis, and bile acid transport and metabolism were compared. 24-norUrsodeoxycholic acid metabolism was studied in serum, liver, bile, and urine. RESULTS: 24-norUrsodeoxycholic acid markedly improved liver tests and liver histology and significantly reduced hydroxyproline content and the number of infiltrating neutrophils and proliferating hepatocytes and cholangiocytes. 24-norUrsodeoxycholic acid underwent extensive phase I/II metabolism (hydroxylation, sulfation, and glucuronidation), thereby increasing the hydrophilicity of biliary bile acid secretion. There was a coordinated induction of bile acid detoxifying enzymes (Cyp2b10, Cyp3a11, and Sult2a1) and efflux pumps (Mrp3 and Mrp4). Ursodeoxycholic acid, in contrast, increased alanine transaminase and alkaline phosphatase levels, had no significant effects on hydroxyproline content, and induced biliary transporters and detoxification enzymes to a much smaller extent than 24-norUrsodeoxycholic acid. CONCLUSIONS: 24-norUrsodeoxycholic acid ameliorates sclerosing cholangitis in Mdr2(-/-) mice. Its therapeutic mechanisms involve (1) increasing the hydrophilicity of biliary bile acids, (2) stimulating bile flow with flushing of injured bile ducts, and (3) inducing detoxification and elimination routes for bile acids.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2006

Valproate inhibition of histone deacetylase 2 affects differentiation and decreases proliferation of endometrial stromal sarcoma cells.

Covalent modifications of histone proteins, in particular deacetylation of lysine residues, are important for the regulation of gene transcription both in normal and malignant cells. These processes are controlled by histone acetyltransferases and histone deacetylases (HDAC) and have up to now not been described in solid mesenchymal tumors. The present study shows differences in the HDAC1 and HDAC2 expression in endometrial stromal sarcomas (ESS) and a cognate cell line (ESS-1) compared with nonneoplastic endometrial stroma. We show for the first time that HDAC2 expression is consistently increased in ESS. In contrast, HDAC1 expression is generally lower than HDAC2 both in nonneoplastic stroma and in ESS, suggesting that these two proteins, although closely related, are regulated in different ways. In vitro experiments with an ESS cell line showed that valproate, an inhibitor of the class I HDACs, led to significant HDAC2 decrease and to cell differentiation. HDAC2 inhibition in ESS-1 cells caused significant changes in the cell cycle by inhibiting G1-S transition and influencing expression of p21WAF1 and cyclin D1. Moreover, in ESS-1 cells, increased expression of the p21WAF1 was associated with reduction of HDAC2 expression after transfection with small interfering RNA directed against HDAC2. Our results suggest that HDAC2 might be considered as potential drug target in the therapy of ESS and that HDAC inhibitors should be further evaluated in clinical trials in ESS.

Cell Differentiation↗

PubMed2006

Lithocholic acid feeding induces segmental bile duct obstruction and destructive cholangitis in mice.

We determined the mechanisms of hepatobiliary injury in the lithocholic acid (LCA)-fed mouse, an increasingly used model of cholestatic liver injury. Swiss albino mice received control diet or 1% (w/w) LCA diet (for 1, 2, and 4 days), followed by assessment of liver morphology and ultrastructure, tight junctions, markers of fibrosis and key proteins of hepatobiliary function, and bile flow and composition. As expected LCA feeding led to bile infarcts, which were followed by a destructive cholangitis with activation and proliferation of periductal myofibroblasts. At the ultrastructural level, small bile ducts were frequently obstructed by crystals. Biliary-excreted fluorescence-labeled ursodeoxycholic acid accumulated in bile infarcts, whereas most infarcts did not stain with India ink injected into the common bile duct; both findings are indicative of partial biliary obstruction. Expression of the main basolateral bile acid uptake proteins (sodium-taurocholate cotransporter and organic anion-transporting polypeptide 1) was reduced, the canalicular transporters bile salt export pump and multidrug-related protein 2 were preserved, and the basolateral transporter multidrug-related protein 3 and the detoxifying enzyme sulfotransferase 2a1 were induced. Thus, we demonstrate that LCA feeding in mice leads to segmental bile duct obstruction, destructive cholangitis, periductal fibrosis, and an adaptive transporter and metabolic enzyme response.

Animals↗

PubMed2005

Coordinated induction of bile acid detoxification and alternative elimination in mice: role of FXR-regulated organic solute transporter-alpha/beta in the adaptive response to bile acids.

The bile acid receptor farnesoid X receptor (FXR) is a key regulator of hepatic defense mechanisms against bile acids. A comprehensive study addressing the role of FXR in the coordinated regulation of adaptive mechanisms including biosynthesis, metabolism, and alternative export together with their functional significance is lacking. We therefore fed FXR knockout (FXR(-/-)) mice with cholic acid (CA) and ursodeoxycholic acid (UDCA). Bile acid synthesis and hydroxylation were assessed by real-time RT-PCR for cytochrome P-450 (Cyp)7a1, Cyp3a11, and Cyp2b10 and mass spectrometry-gas chromatography for determination of bile acid composition. Expression of the export systems multidrug resistance proteins (Mrp)4-6 in the liver and kidney and the recently identified basoalteral bile acid transporter, organic solute transporter (Ost-alpha/Ost-beta), in the liver, kidney, and intestine was also investigated. CA and UDCA repressed Cyp7a1 in FXR(+/+) mice and to lesser extents in FXR(-/-) mice and induced Cyp3a11 and Cyp2b10 independent of FXR. CA and UDCA were hydroxylated in both genotypes. CA induced Ost-alpha/Ost-beta in the liver, kidney, and ileum in FXR(+/+) but not FXR(-/-) mice, whereas UDCA had only minor effects. Mrp4 induction in the liver and kidney correlated with bile acid levels and was observed in UDCA-fed and CA-fed FXR(-/-) animals but not in CA-fed FXR(+/+) animals. Mrp5/6 remained unaffected by bile acid treatment. In conclusion, we identified Ost-alpha/Ost-beta as a novel FXR target. Absent Ost-alpha/Ost-beta induction in CA-fed FXR(-/-) animals may contribute to increased liver injury in these animals. The induction of bile acid hydroxylation and Mrp4 was independent of FXR but could not counteract liver toxicity sufficiently. Limited effects of UDCA on Ost-alpha/Ost-beta may jeopardize its therapeutic efficacy.

Animals↗

PubMed2005

Ovarian granulosa cell tumors frequently express EGFR (Her-1), Her-3, and Her-4: An immunohistochemical study.

OBJECTIVE: Up to 50% of patients with ovarian granulosa cell tumors (GCTs) will develop recurrences; some of these recurrences can be seen as late as 30 years following the initial surgical treatment. Combined chemotherapy and radiotherapy are currently used for patients with advanced or recurrent disease. The aim of this study was to investigate the possible eligibility of patients with GCTs for anti-Her therapy. METHODS: The immunohistochemical expression of EGFR (Her-1), Her-2, Her-3, and Her-4 was analyzed in a group of ovarian GCTs encompassing 38 adult type and 2 juvenile type. RESULTS: Thirty-one cases (77.5%) were positive for at least one of the receptors EGFR (Her-1), Her-3, and Her-4. Twenty-six out of 40 (65%) GCTs showed positive reaction for EGFR (Her-1). Eight tumors (20%) were exclusively positive for EGFR (Her-1). None of 40 cases showed a positive reaction for Her-2. Positive reactions for Her-3 and Her-4 were observed in 18 (45%) and 23 (57.5%) tumors. Only one case (2.5%) was exclusively positive for Her-4. Four tumors (10%) showed positivity for Her-3 and Her-4 but were negative for EGFR (HER-1). While one of the two JGCTs was negative for all members of the Her-family, one showed reactivity for EGFR (Her-1), Her-3, and Her-4. CONCLUSION: In this study, most of the ovarian GCTs express at least one of the receptors EGFR (Her-1), Her-3, and Her-4. These findings provide some evidence to further explore the potential use of agents targeting these receptors (particularly EGFR) in the treatment of ovarian GCTs.

ErbB Receptors↗

PubMed2005

Role of nuclear receptors and hepatocyte-enriched transcription factors for Ntcp repression in biliary obstruction in mouse liver.

Expression of the main hepatic bile acid uptake system, the Na+-taurocholate cotransporter (Ntcp), is downregulated during cholestasis. Bile acid-induced, farnesoid X receptor (FXR)-mediated induction of the nuclear repressor short heterodimer partner (SHP) has been proposed as a key mechanism reducing Ntcp expression. However, the role of FXR and SHP or other nuclear receptors and hepatocyte-enriched transcription factors in mediating Ntcp repression in obstructive cholestasis is unclear. FXR knockout (FXR-/-) and wild-type (FXR+/+) mice were subjected to common bile duct ligation (CBDL). Cholic acid (CA)-fed and LPS-treated FXR-/- and FXR+/+ mice were studied for comparison. mRNA levels of Ntcp and SHP and nuclear protein levels of hepatocyte nuclear factor (HNF)-1alpha, HNF-3beta, HNF-4alpha, retinoid X receptor (RXR)-alpha, and retinoic acid receptor (RAR)-alpha and their DNA binding were assessed. Hepatic cytokine mRNA levels were also measured. CBDL and CA led to Ntcp repression in FXR+/+, but not FXR-/-, mice, whereas LPS reduced Ntcp expression in both genotypes. CBDL and LPS but not CA induced cytokine expression and reduced levels of HNF-1alpha, HNF-3beta, HNF-4alpha, RXRalpha, and RARalpha to similar extents in FXR+/+ and FXR-/-. DNA binding of these transactivators was unaffected by CA in FXR+/+ mice but was markedly reduced in FXR-/- mice. In conclusion, Ntcp repression by CBDL and CA is mediated by accumulating bile acids via FXR and does not depend on cytokines, whereas Ntcp repression by LPS is independent of FXR. Reduced levels of HNF-1alpha, RXRalpha, and RARalpha in CBDL FXR-/- mice and reduced DNA binding in CA-fed FXR-/- mice, despite unchanged Ntcp levels, indicate that these factors may have a minor role in regulation of mouse Ntcp during cholestasis.

Animals↗

PubMed2005

Cytokine-independent repression of rodent Ntcp in obstructive cholestasis.

Cholestatic liver injury is associated not only with accumulation of bile acids but also with activation of proinflammatory cytokines. Common bile duct ligation (CBDL) induces sustained downregulation of the Na(+)/taurocholate cotransporter (Ntcp) in rodent liver. Although repression of Ntcp during endotoxemia is cytokine mediated, it is unclear whether inflammatory cytokines contribute to this downregulation in obstructive cholestasis. Cytokine inactivation in CBDL rats and mice was either performed directly with tumor necrosis factor alpha (etanercept) or interleukin 1 beta inactivation (anakinra/AMG 719) or indirectly Kupffer cell depletion via intraperitoneal administration of liposome-encapsulated dichloromethylene bisphosphonate. Protein and messenger RNA (mRNA) expression of Ntcp and short heterodimer partner (SHP) were analyzed via Western and Northern blotting. Key regulators of Ntcp (hepatocyte nuclear factor 1 alpha [HNF-1alpha], HNF-4alpha, retinoid X receptor alpha [RXRalpha]:retinoic acid receptor alpha [RARalpha]) were studied via electrophoretic mobility shift analysis and nuclear Western blot analysis. Both methods of cytokine inactivation failed to maintain Ntcp protein or mRNA expression within 3 days after CBDL in either rats or mice (20%-40% of sham controls), while SHP mRNA expression increased three- to five-fold. Decreased nuclear HNF-1alpha and HNF-4alpha protein levels (45% and 60% of sham controls, respectively) and HNF-1alpha binding activity (32% of sham controls) were not restored during cytokine inactivation after CBDL, indicating cytokine-independent mechanisms of Ntcp regulation. RXRalpha:RARalpha binding remained unchanged in all experimental conditions. In conclusion, during obstructive cholestasis accumulating bile acids per se, without major contribution of cytokines, leads to downregulation of Ntcp via repression of HNF-1alpha and HNF-4alpha.

Animals↗

PubMed2005

CAR and PXR agonists stimulate hepatic bile acid and bilirubin detoxification and elimination pathways in mice.

Induction of hepatic phase I/II detoxification enzymes and alternative excretory pumps may limit hepatocellular accumulation of toxic biliary compounds in cholestasis. Because the nuclear xenobiotic receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR) regulate involved enzymes and transporters, we aimed to induce adaptive alternative pathways with different CAR and PXR agonists in vivo. Mice were treated with the CAR agonists phenobarbital and 1,4-bis-[2-(3,5-dichlorpyridyloxy)]benzene, as well as the PXR agonists atorvastatin and pregnenolone-16alpha-carbonitrile. Hepatic bile acid and bilirubin-metabolizing/detoxifying enzymes (Cyp2b10, Cyp3a11, Ugt1a1, Sult2a1), their regulatory nuclear receptors (CAR, PXR, farnesoid X receptor), and bile acid/organic anion and lipid transporters (Ntcp, Oatp1,2,4, Bsep, Mrp2-4, Mdr2, Abcg5/8, Asbt) in the liver and kidney were analyzed via reverse-transcriptase polymerase chain reaction and Western blotting. Potential functional relevance was tested in common bile duct ligation (CBDL). CAR agonists induced Mrp2-4 and Oatp2; PXR agonists induced only Mrp3 and Oatp2. Both PXR and CAR agonists profoundly stimulated bile acid-hydroxylating/detoxifying enzymes Cyp3a11 and Cyp2b10. In addition, CAR agonists upregulated bile acid-sulfating Sult2a1 and bilirubin-glucuronidating Ugt1a1. These changes were accompanied by reduced serum levels of bilirubin and bile acids in healthy and CBDL mice and by increased levels of polyhydroxylated bile acids in serum and urine of cholestatic mice. Atorvastatin significantly increased Oatp2, Mdr2, and Asbt, while other transporters and enzymes were moderately affected. In conclusion, administration of specific CAR or PXR ligands results in coordinated stimulation of major hepatic bile acid/bilirubin metabolizing and detoxifying enzymes and hepatic key alternative efflux systems, effects that are predicted to counteract cholestasis.

Animals↗

PubMed2005

p62 protein is expressed in pancreatic beta cells.

p62 is a cellular protein that plays an adapter role in signal transduction pathways involved in such diverse biological functions as proliferation, differentiation, reaction to oxidative stress and immune response. Furthermore, p62 has recently been detected as a component of intracytoplasmic protein aggregates (inclusion bodies), which are hallmarks of a variety of chronic degenerative disorders, such as Parkinson's disease and Alzheimer's disease, but also of steatohepatitis. Here we report that p62 and insulin are co-expressed in a diffuse fashion in beta cells in normal human pancreas as well as in primary chronic pancreatitis and in normal pancreas from mouse and swine. In contrast, p62 protein is absent from, or only focally and very weakly expressed in, insulinomas, glucagonomas or non-functioning pancreatic neuroendocrine tumours or carcinomas that express insulin or other pancreatic as well as extrapancreatic hormones. Although the biological function of p62 in beta cells is unknown, the co-expression of p62 and insulin in non-neoplastic beta cells suggests that, in the beta cell, p62 may play a role in specific insulin-related signalling. Since p62 may also be involved in pro-apototic signal transduction, the loss of p62 expression in neuroendocrine neoplasms of the pancreas may render the tumour cells less sensitive to pro-apototic signals. Further research is necessary to elucidate the role of p62 in beta cell-specific signal transduction.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Interaction of stress proteins with misfolded keratins.

Misfolded and aggregated proteins are a characteristic feature of a variety of chronic diseases. Examples include neurofibrillary tangles in Alzheimer disease, Lewy bodies in Parkinson disease and Mallory bodies (MBs) in chronic liver diseases, particularly alcoholic and non-alcoholic steatohepatitis (ASH and NASH). MB formation is at least in part the result of chronic oxidative cell stress in hepatocytes and can be induced in mice by long-term intoxication with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). Proteomic analysis revealed that MBs consist of ubiquitinated keratins and the stress proteins Hsp70, Hsp25, and p62. Furthermore, marked overexpression of clusterin, which shares functional properties with small heat shock proteins, was identified by gene expression profiling of DDC-treated mice livers. To investigate whether clusterin has a function in the stress response to misfolded keratins, we performed transfection studies utilizing expression constructs encoding ubiquitin, p62, Hsp27, clusterin, keratin 8, and keratin 18. Ubiquitin was found in a strong and constant association with keratin aggregates, whereas binding of p62 to keratin was variable. Hsp27 did not colocalize with keratin aggregates under these experimental conditions. In contrast, clusterin associated with misfolded keratin only if its signal peptide was deleted and its secretion inhibited. This suggests that clusterin has ability to bind misfolded proteins, including keratins but its physiological function is restricted to the extracellular space. The extracellular localization of clusterin was underlined by immunohistochemical studies in Alzheimer disease brains, where clusterin was constantly found in association with amyloid plaques; in contrast, cytoplasmic inclusions such as neurofibrillary tangles as well as MBs in ASH were negative. Furthermore, we found clusterin in association with elastic fibers in the extracellular matrix in several chronic liver diseases, including ASH and alpha1-antitrypsin deficiency, implying a possible role of clusterin in liver fibrosis.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Oncosis represents the main type of cell death in mouse models of cholestasis.

BACKGROUND/AIMS: Since the mechanisms leading to hepatocyte death in cholestasis are not well defined, we aimed to obtain closer insights into the related pathogenetic principles. METHODS: Cell death was assessed in common bile duct ligated (CBDL) and cholic acid (CA)-fed mice, and compared to Fas agonist Jo2-injected mice by studying H and E-stained tissue sections, DNA ladder analysis, caspase-3-like activity assay, immunohistochemistry, double immunofluorescence microscopy for activated caspase-3 and cytokeratin (CK) 18, the TUNEL method, and electron microscopy. RESULTS: Jo2-treated mice showed activation of caspase-3, breakdown of the CK intermediate filament network, and classical morphological features of apoptosis. In contrast, in CA-fed and CBDL mice, oncosis characterized by cell swelling and ruptured cell membranes was the predominant type of cell death, whereas in both experimental conditions significant activation of caspase-3 was absent and typical CK alterations were rare despite frequent positivity of the TUNEL assay. CONCLUSIONS: (i) Oncosis represents the main type of hepatocyte death in acute cholestasis in mice. (ii) The importance of apoptosis in cholestasis may be overestimated if non-specific detection systems (e.g. TUNEL assay) are used.

Animals↗

PubMed2005

Chromosomal alterations in low-grade endometrial stromal sarcoma and undifferentiated endometrial sarcoma as detected by comparative genomic hybridization.

OBJECTIVE: Endometrial stromal sarcomas (ESS) are very rare neoplasms constituting less than 0.5% of all malignant uterine tumors. The aim of the present study was to characterize the karyotypic abnormalities in these malignant mesenchymal tumors and to find specific chromosomal aberrations with eventual correlation with histologic grades. METHODS: Twelve cases of endometrial stromal sarcomas consisting of nine low-grade ESS and three undifferentiated endometrial sarcomas (UES) were investigated by comparative genomic hybridization (CGH). RESULTS: Ten of the twelve cases (83.3%) displayed chromosomal gains or losses. Deletions occurred more frequently than gains (63.4% versus 36.6%). In low-grade ESS, gains on 1, 6q, 9q, 16p, 19, 20q, 22q and losses on 2, 4q, 6, 7, 11q, 13q, 15q, 16q, 20p, X were detected. CGH with UES exhibited gains on 2q, 4q, 6q, 7p, 9q, 20q and losses on 3q, 10p, 14q. One low-grade ESS and one UES did not reveal any chromosomal aberration. CONCLUSIONS: Chromosomal aberrations in endometrial sarcomas are heterogeneous and do not clearly correlate with the histologic grades. There is no increased accumulation of aberrations from low-grade ESS to UES. Despite the karyotypic variations, chromosomal deletion on 7p was the most common finding (55.6%) in low-grade ESS and may play a role in tumor development and progression.

Chromosome Aberrations↗

PubMed2005

JAZF1/JJAZ1 gene fusion in endometrial stromal sarcomas: molecular analysis by reverse transcriptase-polymerase chain reaction optimized for paraffin-embedded tissue.

Endometrial stromal tumors are rare uterine neoplasms including benign stromal nodules, low-grade endometrial stromal sarcomas (ESS), and undifferentiated endometrial sarcomas (UES), the latter representing the most aggressive form. Morphological characteristics and cytogenetic abnormalities are heterogeneous, making diagnosis difficult. Recently, a gene fusion on chromosome 7 that includes two zinc-finger genes (JAZF1 and JJAZ1) has been discovered in these tumors. Hitherto only 31 cases, described by three different research groups, have shown JAZF1/JJAZ1 fusion in approximately 50% of all analyzed low-grade ESSs whereas it is less frequent in UESs. In this study we analyzed 20 ESS and 2 UES cases using two-step reverse transcriptase-polymerase chain reaction optimized for formalin-fixed, paraffin-embedded tissue. In our subset of samples, the JAZF1/JJAZ1 fusion transcript occurred in 80% of analyzed ESS cases and in none of two UES cases. In comparison to published data, our results identified the JAZF1/JJAZ1 gene fusion more frequently in endometrial stromal tumors than hitherto presumed. This cytogenetic abnormality was not present in normal endometria, leiomyomas, or leiomyosarcomas or in lung, gastric, or hepatic carcinomas, indicating its specificity for endometrial stromal tumors. In combination with other established methods, accurate reverse transcriptase-polymerase chain reaction analysis of JAZF1/JJAZ1 gene fusion may be useful in diagnosing difficult or unusual ESS/UES cases.

Artificial Gene Fusion↗

PubMed2005

Metaplastic breast carcinomas: are they of myoepithelial differentiation?: immunohistochemical profile of the sarcomatoid subtype using novel myoepithelial markers.

We investigated 20 spindle cell (sarcomatoid) metaplastic carcinomas (MCs) without squamous differentiation. In addition, five high-grade phyllodes tumors were assessed for comparison. Our immunohistochemical antibody panel included pan-cytokeratin (CK), low molecular weight CK (CK8/18), four basal cell type CKs (34betaE12, CK5/6, CK14, and CK17), vimentin antibodies, as well as antibodies to established (SMA, CD10, p63, S-100, maspin, calponin, GFAP, SM-myosin), and novel (CD29, 14-3-3sigma) myoepithelial markers. Sixteen of the 20 tumors (80%) expressed at least two markers of the combination CD10/p63/SMA. S-100 detected 1 case negative for CD10/p63/SMA and 3 cases that only expressed one marker of this combination. While 18 MCs (90%) were positive for CD29, 14-3-3sigma (11 cases) and maspin (9 cases) were observed in 55% and 45%, respectively. Antibodies to pan-CK and the basal cell type CKs were strongly reactive in 12 tumors (60%), but in 6 cases (30%) positivity for these markers was weak and only focal; 2 MCs showed no positivity for CK. The stromal component of all phyllodes tumors was positive for vimentin, whereas all other investigated markers were absent except for focal p63 and CD10 expression in 1 case each. Our findings convincingly show a myoepithelial immunophenotype in sarcomatoid MCs, which is demonstrated by the presence of basal cell type CKs and the combination of the established myoepithelial markers CD10, p63, SMA, and S-100. We conclude that tumors with weak or even absent CK expression should only be diagnosed as primary sarcomas of the breast after exclusion of a myoepithelial immunophenotype. CD29 and 14-3-3sigma represent valuable novel myoepithelial markers in these diagnostically difficult cases.

14-3-3 Proteins↗

PubMed2005

Endometrial stromal sarcomas frequently express epidermal growth factor receptor (EGFR, HER-1): potential basis for a new therapeutic approach.

Endometrial stromal sarcomas are rare malignant mesenchymal uterine tumors. The expressions of different epidermal growth factor receptors such as EGFR (HER-1), HER-2, HER-3, and HER-4 have not yet been examined in these tumors. Twenty-three cases of endometrial sarcomas consisting of 20 low-grade endometrial stromal sarcomas and 3 undifferentiated endometrial sarcomas were examined immunohistochemically for EGFR (HER-1), HER-2, HER-3, and HER-4. EGFR (HER-1) was positive in 17 of 23 (74%) cases. While the three undifferentiated endometrial sarcomas were positive for EGFR, 14 of 20 (70%) low-grade endometrial stromal sarcomas showed positive reactions for EGFR. All examined cases were negative for HER-2, HER-3, and HER-4. This study is the first to show common expression of EGFR (HER-1) in endometrial stromal sarcomas. This finding may provide the basis for a new therapeutic strategy using monoclonal antibodies against EGFR (such as cetuximab) or small molecule inhibitors of EGFR (such as gefitinib) in patients with endometrial sarcomas.

Biomarkers, Tumor↗

PubMed2005

Hepatobiliary transporter expression in human hepatocellular carcinoma.

BACKGROUND/AIMS: Treatment of hepatocellular carcinoma (HCC) is hampered by resistance to chemotherapy, which might be mediated by multidrug resistance P-glycoproteins (MDR P-gps) and MDR-associated proteins (MRPs). The effectiveness of cytostatics could be further impeded by reduced hepatocellular drug uptake into HCCs. Therefore, we aimed to determine P-gp, MRP and organic anion transporting protein OATP2 (SLC21A6) expression in HCC. Furthermore, we investigated expression of the major bile salt uptake system Na(+)/taurocholate cotransporter NTCP (SLC10A1), since bile salt-coupled chemotherapeutics were proposed to increase therapeutic drug enrichment in HCC. MATERIAL/METHODS: mRNA and protein expression and tissue distribution of P-gps, MRPs, OATP2 and NTCP were assessed in HCC and peritumorous non-neoplastic tissue by reverse transcription polymerase chain reaction, Western blotting and immunohistochemistry, respectively. RESULTS: Expression of P-gps (multidrug export pump MDR1 (ABCB1), phospholipid flippase MDR3 (ABCB4), sister of P-glycoprotein SPGP (ABCB11)) and basolateral MRP homologue MRP3 (ABCC3) showed a trend for decreased levels in HCC but was highly variable among individual tumors. In contrast, canalicular conjugate export pump MRP2 (ABCC2) expression was generally maintained or even showed a trend towards increased levels. NTCP and OATP2 expression was markedly reduced in most HCCs (P < 0.05). Expression of the genuine drug transporter, the concentrative nucleoside transporter (CNT1), was highly variable and showed a trend for reduced levels in HCC. SUMMARY/CONCLUSIONS: MRP2 seems to be the major candidate transporter involved in chemoresistance and reduced expression of OATP2 may further contribute to low drug accumulation in HCCs. Overexpression of drug exporters is not a general feature of HCC but could account for chemoresistance of individual cases. Since expression of uptake systems is generally reduced in HCC, bile salt-coupled therapeutics may not represent a suitable strategy to overcome insufficient drug enrichment.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2004

Wilson disease.

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism. Since daily copper intake exceeds the body's requirements, effective means of excreting excess copper are essential. These are accomplished by ATP7B, a new member of the cation-transporting p-type ATPase family, which is mainly expressed in the liver and mediates both copper secretion into plasma (coupled with ceruloplasmin synthesis) and its excretion into bile. Thus far, more than 200 mutations of the WD gene have been detected, causing impairment of ATP7B function and, ultimately, copper accumulation. Excess copper, however, induces free-radical reactions and lipid peroxidation. Resultant liver damage leads to steatosis, inflammation, cirrhosis, and, occasionally, fulminant liver failure. The diagnosis of WD is commonly made on the basis of typical clinical and laboratory findings, including low serum ceruloplasmin, increased urinary copper excretion, and increased hepatic copper content. Since liver morphology is non-specific, and copper histochemistry may lead to both false-negative and false-positive results, the pathologist usually only suspects the disease or assists in its confirmation. Although the value of molecular genetic testing is limited due to the high number of possible gene mutations, polymerase chain reaction may be useful for the evaluation of family members of homozygous index patients.

Copper↗

PubMed2004

Expression of androgen receptors in benign and malignant endometrial stromal neoplasms.

Several studies have shown that endometrial stromal neoplasms express estrogen and progesterone receptors (ER, PR). To our knowledge, the presence or absence of androgen receptors (AR) in these rare uterine neoplasms has not been investigated. Tumors ( n=20)-3 endometrial stromal nodules, 14 low-grade endometrial stromal sarcomas (ESS, low grade), and 3 high-grade endometrial sarcomas (undifferentiated endometrial sarcoma, UES)-were studied. Immunohistochemical analyses for ER, PR, and AR were performed on formalin-fixed, paraffin-embedded archival material. Positive immunoreactions for ER and PR were observed in 14 (70%) and 17 (85%) cases, respectively. Furthermore, 9 cases (45%) were positive for AR. Among 17 ESS and UES cases, 7 (41%) revealed positivity for AR. Two of three benign stromal nodules were also positive for AR. Moreover, one of the three high-grade sarcomas (undifferentiated endometrial sarcoma) was negative for both ER and PR, but showed positive reaction for AR. In summary, ARs are expressed in 45% of endometrial stromal neoplasms. In addition to determination of ER and PR, the results of immunohistochemical examination of AR in these rare uterine tumors may have some impact on the postoperative management of the patients.

Biomarkers, Tumor↗